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.\" @(#)bindresvport.3n 2.2 88/08/02 4.0 RPCSRC; from 1.7 88/03/14 SMI

.\" $FreeBSD: src/lib/libc/rpc/bindresvport.3,v 1.10 2000/01/27 02:55:01 bde Exp $

.\"

.Dd January 27, 2000

.Dt BINDRESVPORT 3

.Os

.Sh NAME

.Nm bindresvport ,

.Nm bindresvport_sa

.Ndbind a socket to a privileged IP port

.Sh SYNOPSIS

.Fd #include 

.Ft int

.Fn bindresvport "int sd" "struct sockaddr_in *sin"

.Ft int

.Fn bindresvport_sa "int sd" "struct sockaddr *sa"

.Sh DESCRIPTION

.Fn bindresvport

and

.Fn bindresvport_sa

are used to bind a socket descriptor to a privileged

.Tn IP

port, that is, a

port number in the range 0-1023.

.Pp

Only root can bind to a privileged port; this call will fail for any

other users.

.Pp

When

.Va sin

is not null,

.Va sin->sin_family

must be initialized to the address family of the socket, passed by

.Va sd .

If the value of sin->sin_port is non-zero

.Fn bindresvport

will attempt to use that specific port.  If it fails, it chooses another

privileged port automatically.

.Pp

It is legal to pass null pointer to

.Va sin .

In this case, the caller cannot get the port number

.Fn bindresvport

has picked.

.Pp

Function prototype of

.Fn bindresvport

is biased to

.Dv AF_INET

socket.

.Fn bindresvport_sa

acts exactly the same, with more neutral function prototype.

Note that both functions behave exactly the same, and

both support

.Dv AF_INET6

sockets as well as

.Dv AF_INET

sockets.

.Sh RETURN VALUES

.Fn bindresvport

and

.Fn bindresvport_sa

return 0 if they are successful, otherwise \-1 is returned and

.Va errno

set to reflect the cause of the error.

.Sh ERRORS

The

.Fn bindresvport

and

.Fn bindresvport_sa

functions fail if:

.Bl -tag -width Er

.It Bq Er EBADF

.Fa sd

is not a valid descriptor.

.It Bq Er ENOTSOCK

.Fa sd

is not a socket.

.It Bq Er EADDRNOTAVAIL

The specified address is not available from the local machine.

.It Bq Er EADDRINUSE

The specified address is already in use.

.It Bq Er EINVAL

The socket is already bound to an address,

or the socket family and the family of specified address mismatch.

.It Bq Er EACCES

The requested address is protected, and the current user

has inadequate permission to access it.

.It Bq Er EFAULT

The

.Fa name

parameter is not in a valid part of the user

address space.

.It Bq Er ENOBUFS

Insufficient resources were available in the system

to perform the operation.

.It Bq Er EPFNOSUPPORT

The protocol family has not been configured into the

system, no implementation for it exists,

or address family did not match between arguments.

.El

.Sh "SEE ALSO"

.Xr bind 2 ,

.Xr socket 2 ,

.Xr rresvport 3 ,

.Xr rresvport_af 3